A number of publishers say Apple News is sending them a significant traffic boost in the past month, but it’s doing little to help them monetize it.

Publishers say traffic has boomed since the mobile news aggregation app was refreshed as part of an iOS 10 update in mid-September. As part of that update, the app was designed to be bolder and include breaking news notifications and better organization of the main “For You” section.

Several news publisher clients reported they’re getting more audience from Apple News than from Google AMP, the search giant’s fast-loading mobile article initiative, according to Polar, a native ad platform, which is testing branded content promotion in Apple News with a small number of publishers.

The Atlantic and The Guardian, for example, both said their traffic increased significantly in the past month, doubling in The Atlantic’s case. The publishers didn’t share actual numbers.

But there’s little advertising today on Apple News, because it’s difficult for publishers to monetize that traffic. As of this summer, Apple News is displaying articles that appear in the left-of-home screen right in the app itself rather than sending traffic to publishers’ own mobile sites, making Apple News like Facebook Instant Articles or Google AMP in that articles are read inside the platform rather than on the publisher’s own site.

“Many publishers aren’t benefiting from the mobile web traffic the way in which they had prior to iOS 10,” said Anthony DeMaio, vp of global advertising for The Washington Post.

Publishers can sell ads on Apple News themselves and keep all the ad revenue, but to do so, they have to use Apple’s ad server, Workbench, which is a hassle because it requires ads to be built a special way. One mobile ad platform, Kargo, is helping publishers monetize Apple News by formatting ads so they’re easily accepted by Apple’s ad server.

Apple News also still doesn’t have comScore tracking, according to publishers, despite having said it would implement it last spring. Apple is well known for putting user security first, and rejected comScore tracking because of privacy concerns, one publisher said, speaking on condition of anonymity. ComScore hasn’t replied to a request for comment.

Apple is expected to release comScore data to publishers soon, said a source with direct knowledge of the plans. Until then, though, the only source of publisher traffic is from Apple itself, which is providing data such as number of users and how much articles are being shared.

But some sources said Apple has been talking to publishers about letting them use their own serving platforms instead of Apple’s.

Digital publishing executives said Apple has been talking about making it easier to sell advertising on Apple News, including letting publishers use their own ad serving platform. “They have been more proactive in speaking with us about monetization,” one exec said.

Publishers would welcome that, said Ryan McConville, president and COO of Kargo. “Any time publishers are asked to use multiple ad servers, it makes monetization harder. Publishers clearly see the benefits of audience extensions across third-party platforms like Apple News or [Facebook Instant Articles], but inevitably that is also weighed against the difficulty of monetization in those ecosystems.”